System for transmitting information via electric lines and method for operating the system

ABSTRACT

In a system and method for operating a system, a drive is connectable to a supply-voltage source, especially an AC-voltage source, with the aid of an apparatus, in particular a control unit, via electric lines installed in the system, and information is transmittable between the control unit and the drive, using the lines.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent application Ser. No. 12/446,116, filed on Apr. 17, 2009, which is the national stage entry of International Application No. PCT/EP2007/007736, filed on Sep. 5, 2007, which claims priority to German Patent Application No. 10 2006 049 507.1, filed on Oct. 17, 2006, each of which is incorporated herein in its entirety by reference thereto.

FIELD OF THE INVENTION

The present invention relates to a system for transmitting information via electric lines and a method for operating a system for transmitting information via electric lines.

BACKGROUND INFORMATION

Drives often include electric motors which are powered via three-phase lines. Therefore, many systems are designed to be cabled with three-phase lines. However, for transmission of information going beyond switching-off and switching-on operations, further cabling like, for example, fieldbus cabling must be provided.

SUMMARY

Example embodiments of the present invention provide a system in terms of the transmission of information.

According to example embodiments of the present invention, a system includes a drive or another device which is connectable to a supply-voltage source, particularly an AC voltage source, with the aid of an apparatus, especially a control unit, via electric lines installed in the system, information being transmittable between the control unit and the drive or other device, using the lines.

The advantage in so doing is that the supply lines are used, together with their connections to the power supply system. Therefore, the signal frequency used is low-frequency, thus far below 100 Hz, especially far below 60 Hz in the U.S. area or 50 Hz in the European area. The advantage in this case lies in the long range of the information transmission and in the reliability of the data transfer. The reason is that since the system voltages themselves are used, a reliable, error-free recognition of the information is made possible. In addition, the transmission range is considerable in comparison to high-frequency modulation applications.

A further advantage is that components for implementing example embodiments of the present invention may be selected to be very inexpensive and uncomplicated. This is because supply voltages may be easily recognized and determined, especially in comparison to the recognition of high-frequency signals with correspondingly costly signal electronics suitable for high frequencies, together with coupling and decoupling elements or antennas.

In example embodiments, the drive includes devices for measuring the supply voltages assigned to the lines. The advantage here is that resistive series circuits may be used, which are inexpensive and uncomplicated to produce. The measured value is then able to be acquired and processed by an analog-to-digital converter. Alternatively, an analog averaging with the aid of a low-pass filter is also usable, and threshold values may be compared in either digital or analog fashion.

In example embodiments, three lines are used, the drive providing a device for measuring the voltage between each line and a reference potential. This offers the advantage that the simple acquisition of measured values is sufficient, and therefore the present invention is practicable without special expenditure.

In example embodiments, the apparatus includes a half-wave control, particularly for at least one of the three lines. This is advantageous in that the system voltage itself is used, and the positive as well as negative half-waves are usable as medium.

In example embodiments, device(s) are at least provided for forming the difference between two of the measured voltages. The advantage in this case is that, by forming the difference, a reliable recognition of the states is feasible, and therefore a low-error or error-free recognition of the information is feasible.

In example embodiments, a device for curve evaluation, in particular, device(s) for averaging are provided. The advantage here is that the transmitted information is recognizable reliably and in error-free or low-error fashion in the time characteristic of the measured values.

In example embodiments, amplification, especially multiplication by a factor, is provided as a device for the curve evaluation, this factor in particular being selected such that the amplified values are uniquely assigned to the information to be transmitted, especially either after averaging the amplified values or after curve evaluation, at least the determination of a sign reversal being provided in the case of the curve evaluation, as well. Advantageously, a reliable differentiation between the states is thus made possible in a very simple manner.

In example embodiments, device(s) are provided for the comparison with threshold values, the result of the comparison being usable as transmitted information. The advantage in this case is that the threshold values have sufficient distance from each other, and therefore the error rate in recognizing the states is low.

In example embodiments, a three-phase cable is usable as lines. This is advantageous in that the cabling already available in the system may be used unchanged, thus, retrofitting of an existing system is practicable.

In example embodiments, during the time interval in which information is transmitted, the drive is fully powered only by two of the three phases. This has the advantage that a certain, albeit slightly reduced power is able to be made available for the drive during the period of time the data is being transmitted, as well.

In example embodiments, the information is transmittable on the third phase, which is able to be shifted by the apparatus to different states one after another in time for coding the information. This is advantageous in that two of the phases continue to be usable for the transfer of energy, and the third phase is usable for the reliable transfer of data, using the system voltages.

In example embodiments, a first state is the blocking of negative current components, and a second state is the blocking of positive current components. The advantage here is that signals are used which are recognizable easily, clearly and in fail-safe manner, and which include components of the system-voltage characteristic and/or system-current characteristic.

In example embodiments, a third state is not to connect the third phase, thus, to block the current, and a fourth state is to completely conduct the current. This is advantageous in that even full power is able to be transmitted.

In example embodiments, the drive includes signal electronics for receiving and decoding the information. The advantage here is that these signal electronics are able to be integrated into the signal electronics of the drive converter.

In example embodiments, the drive includes an electronic circuit for reversing the sense of rotation of the three-phase power supply. This offers the advantage that a converter or soft-start device is usable in the same way as a controllable polarity-reversal device that is operable in controllable manner for exchanging two phases. In the case of the polarity-reversal device, electronic or perhaps electromechanical power switches may be used.

In example embodiments, the drive has an electronic circuit for influencing the rotary motion of the rotor of the electric motor, in particular, the circuit includes a motor switch, soft start or converter. This is advantageous in that the drive is implemented with intelligence, that is, a computer and associated memory, and therefore it is possible to integrate a complex control unit and/or regulating unit which executes many tasks independently. Consequently, it is sufficient to transmit only small amounts of data or commands to the drive.

In example embodiments, during the time interval in which information is transmitted, the two of the three phases for powering the drive change, and in the same manner, the third phase changes such that the two other phases are always provided for powering the signal electronics of the drive, and the third phase is provided for transmitting the information. The advantage in this case is that a clear separation of functions is provided, and therefore, a decoupling of power and information transmission.

In example embodiments, the apparatus has a series connection of power switches assigned to the third phase, particularly for blocking or letting through the positive and negative current components. This offers the advantage that a simply implemented half-wave control is usable.

In example embodiments, the power switches are able to be driven by a control. Of advantage in this case is that this control is connectable to a superordinate SPC or a central computer, and therefore data is able to be transmitted.

In example embodiments, the drive includes a rectifier, fed from the lines, whose unipolar, especially rectified output voltage has a negative and positive potential. In particular, the signal electronics of the drive are provided at the negative potential; the voltage between the electrical contacts of the components of the signal electronics and the negative potential in particular is always lower in terms of absolute value than the voltage to the positive potential. This is advantageous in that the signal electronics may be placed at such a potential as reference potential, and therefore the voltages of the lines are able to be measured relative to this potential.

Among features with regard to the method for operating a system are that it includes a drive which is connectable to a supply-voltage source, especially an AC voltage source, with the aid of an apparatus, in particular a control unit, via electric lines installed in the system, information being transmitted between the control unit and the drive via the lines, the supply voltages assigned to the lines being measured, the difference being formed between at least two of the measured voltages, a curve evaluation being implemented.

In this context, it is advantageous that a simple procedure is used, such as subtraction and curve evaluation. Therefore, the expenditure is low, recognizability of the information is good and the error rate is low.

In example embodiments, at least at the beginning, that one of the lines is recognized on which the information is transmitted, particularly by comparing average values of the voltage characteristics of the phases. This is advantageous because that phase is recognizable on which the information is transmitted.

Therefore, at the beginning in a first period of time, that phase on which the information is coded is determined, and thereupon, the information is then able to be transmitted. In this context, further measures such as subtraction and, in particular, curve evaluation, as well, are necessary only for the phase recognized as relevant for the information transfer. Measures like subtraction with respect to the other phases further refine the method as to data transmission; in particular, reliability in recognizing a state is also thereby improved, thus, the error rate is reduced.

In example embodiments, averaging is carried out as curve evaluation. This is advantageous in that an extremely low expenditure is needed.

In example embodiments, comparison is carried out with threshold values, and the result of the comparison is used as transmitted information. The advantage in this case is that by performing a comparison with suitable threshold values, the states are clearly recognizable. Advantageously, in the case of four states, three threshold values are to be set. However, since one or more threshold values are also able to be provided for each state, it is advantageous to set them closely around the measured values to be anticipated. Consequently, error detectability is then improved.

Further features, aspects, and advantages are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a system according to an example embodiment of the present invention.

FIG. 2 shows an example of measured-value characteristics for a first circuit state where current is blocked.

FIG. 3 shows an example of measured-value characteristics for a second circuit state where only a positive circuit is enabled.

FIG. 4 shows an example of measured-value characteristics for a third circuit state where only a negative circuit is enabled.

FIG. 5 shows an example of measured-value characteristics for a fourth circuit state where the current is fully conducted.

LIST OF REFERENCE CHARACTERS

-   1 control -   2 apparatus -   3 converter -   4 voltage sensing -   5 rectifier for three-phase current -   6 control signal -   L1, L2, L3 supply lines -   L1*, L2*, L3* measured values

DETAILED DESCRIPTION

Example embodiments of the present invention are explained in more detail below with reference to the figures.

FIG. 1 shows a system according to example embodiments of the present invention. An apparatus 2 is provided which includes switches (S1, S2) for blocking or letting through the positive or negative half waves of a phase.

Switches (S1, S2) are driven from a control, which is to transmit an information stream, entering it as control signal 6, to a drive with the aid of the associated supply line.

The drive includes at least one converter 3 for the supply of an electric motor. The drive includes the electric motor, preferably in the type of construction integrated with converter 3.

In example embodiments of the present invention, the drive is also able to be implemented with a gear unit as a compact drive. Thus, only a single housing is needed for the gear unit, driven by the electric motor, together with converter 3. Such a drive is therefore able to be supplied both with energy and with information via its system supply lines.

The converter according to FIG. 1 is powered via supply lines (L1, L2, L3). Apparatus 2 according to FIG. 1 is implemented such that switches (S1, S2) are each connected in parallel to a diode, and are connected in series to each other. Therefore, in a first circuit state, entire supply line L3 is interrupted. In a second circuit state, only the positive half wave is enabled; in a third, only the negative. In a fourth circuit state, the supply line is able to be provided for conducting the full current.

The four circuit states are used for coding the information to be transmitted.

In so doing, it is provided that the specific circuit state be reliably recognized in the area of the drive.

The indicated converter of the drive includes a rectifier 5 for three-phase current, to which a smoothing capacitor is assigned on the output side. From the “intermediate circuit voltage” applied to this capacitor, an inverter, not shown, at an output stage of the converter is also supplied, which in turn supplies the electric motor.

Voltage sensing 4 acquires measured values (L1*, L2*, L3*), which represent the voltage of supply lines (L1, L2, L3) against the negative potential of rectifier 5.

Each of the measured values is evaluated. In an exemplary embodiment according to the present invention, in so doing, the respective average value is formed. The smallest of the three average values is measured at phase L3 at which the different circuit states are used for coding the information to be transmitted. Only in the fourth circuit state is the phase L3 indistinguishable from the other two phases (L1, L2).

Advantageously, the average value is formed over a time span which corresponds to one or more line periods, thus, 20 ms or an integral multiple thereof at 50 Hz. Preferably, however, the time span is selected such that it also represents an integral multiple of one line period of another electrical network. Thus, for example, a selection of 100 ms is advantageous, since the apparatus is therefore usable at 50 Hz and at 60 Hz.

Consequently, recognition of the phase relevant for the information transfer is made possible in a simple manner by generating the mean value of the associated voltage.

Moreover, after recognition of the phase transmitting the information, the difference is formed of recognized phase L3 with respect to one of the two other phases (L1, L2). In FIGS. 2, 3, 4, 5, exemplary measured-value characteristics are represented for the first, second, third and fourth circuit states. In so doing, the difference of phase L3 with respect to phase L1 is represented by reference numeral 20. The averaging is applied to these characteristics. In this manner, a reliable recognition of the states of the phase containing the information is made possible; the error rate during the transfer of data is thus reducible, as well.

Each of the four circuit states is able to be characterized by threshold values. Even if interference voltages occur, the threshold values are so far from each other that an unequivocal and reliable recognition of the circuit states is feasible. This is a special advantage of this method.

After recognition of the specific circuit state, the drive evaluates the next, also as a function of the previous. A general data transmission is therefore made possible, as well. Thus, not only is information for a stop command, a manual control, a clockwise rotation and a counterclockwise rotation of the motor able to be transmitted, but also even further information such as an error reset or the like. This further information is able to be coded clearly and unmistakably in the time sequence of the circuit states.

The control signal for control 1 is usable, for example, as a 0 volt or 24 volt signal. However, other types of signals are also usable.

According to example embodiments of the present invention, systems in which a three-phase cable was already installed are able to be retrofitted by using the apparatus described herein and replacing the drive by one as described herein.

Example embodiments of the present invention also provide the advantage that the evaluating signal electronics are able to be provided at the potential of the negative potential of the intermediate circuit voltage. Thus, the entire control electronics of the converter are able to be provided there, together with the signal electronics.

The measured-value signals are able to be evaluated in either analog or digital fashion. In the last-named case, to that end, the signal electronics include at least one analog-to-digital converter.

In further exemplary embodiments of the present invention, instead of the averaging, another curve evaluation of the measured-value characteristics is carried out. For instance, the measured value of phase L3 is amplified by a suitable factor. In so doing, the factor is selectable such that in the second circuit state, the positive maximum value is permanently present, in the third, the negative maximum value, in the first, a value which is clearly different from zero and lies between the positive and negative maximum value, and in the fourth, a value which lies in a narrow range around zero.

In further exemplary embodiments of the present invention, instead of the averaging, a different curve evaluation is carried out.

In additional exemplary embodiments of the present invention, the drive is an inverter motor or a gearmotor or an inverter gearmotor. Alternatively, the drive is implemented as a simple electric motor; in that case, however, only the input power is able to be supplied according to the four circuit states.

In further exemplary embodiments according to the present invention, control S is provided with elements for the input of information such as switches, push buttons, slides or rotary knobs or the like. Preferably, therefore, one knob is provided for clockwise rotation and one knob is provided for counterclockwise rotation. Control signals are generated and coded accordingly.

In exemplary embodiments of the present invention, control 1 is connected to a bus system, including a 24 volt supply line. The control signals are thus then able to be generated and coded by a superordinate control.

Apparatus 2 is thus arranged as a type of electronic control unit.

In exemplary embodiments of the present invention, instead of the three-phase line, a single-phase supply line is used. In this instance, the information transmission functions in an analogous manner.

In exemplary embodiments according to the present invention, instead of the drives or converters 3, different devices are connected to which information is transmitted in the same manner as described in the case of the drives. In particular, counting devices such as electricity meters or gas meters are usable as such devices. A time-dependent determination of consumption and/or a remote control and/or remote query of such counting devices is thus made possible. 

1-28. (canceled)
 29. A system, comprising: an apparatus, including a control unit, connectable to a multi-phase AC supply-voltage source; and a device connected to the apparatus via a plurality of lines, each line corresponding to a respective phase of the AC supply-voltage source, each line adapted to supply AC voltage from the apparatus to the device to power the device, a single one of the lines adapted to transmit information between the control unit and the device; wherein the device includes a voltage-measurement device adapted to measure voltage on each of the plurality of lines, the device including a curve evaluation device adapted to evaluate the measured voltage associated with the single one of the lines adapted to transmit information between the control unit and the device, the curve evaluation device including an amplifier adapted to amplify the measured voltage associated with the single one of the lines adapted to transmit information between the control unit and the device by a factor to an amplified value to uniquely identify information transmitted between the control unit and the device.
 30. The system according to claim 29, wherein the device is arranged as (a) a drive, (b) a counting device, (c) a gas meter, (d) an electricity meter, and/or (e) a household electrical device.
 31. The system according to claim 30, wherein the drive includes a measurement device adapted to measure supply voltages assigned to the lines.
 32. The system according to claim 30, wherein three lines are provided, the voltage-measurement device adapted to measure voltage between each line and a reference potential.
 33. The system according to claim 29, wherein the apparatus includes at least one of (a) a half-wave control and (b) a half-wave control for at least one of three lines.
 34. The system according to claim 29, further comprising a difference device adapted to form a difference between two measured voltages.
 35. The system according to claim 29, wherein the curve evaluation device is adapted to determine a sign reversal.
 36. The system according to claim 29, further comprising a comparator adapted for comparison with threshold values, the information including a result of the comparison.
 37. The system according to claim 29, wherein, during a time interval in which information is transmitted, the device is fully powerable by only two of three phases.
 38. The system according to claim 29, wherein the apparatus is adapted to shift the single one of the lines adapted to transmit information between the control unit and the device to different states one after another in time to code and transmit the information.
 39. The system according to claim 38, wherein a first state is a blocking of negative current components, and a second state is a blocking of positive current components.
 40. The system according to claim 39, wherein a third state is completely blocking current, and a fourth state is completely passing the current through.
 41. The system according to claim 29, wherein the device includes signal electronics adapted to receive and decode the information.
 42. The system according to claim 30, wherein the drive includes an electronic circuit adapted to reverse a sense of rotation of a three-phase supply.
 43. The system according to claim 30, wherein the drive has an electronic circuit adapted to influence a rotary motion of a rotor of an electric motor, including (a) a motor switch, (b) a soft start, and/or (c) a converter.
 44. The system according to claim 29, wherein during a time interval in which information is transmitted, two of three phases for powering the drive change, and a third phase changes such that the two other phases are always provided to power signal electronics of the drive, and the third phase is provided for transmitting the information.
 45. The system according to claim 29, wherein the apparatus includes a series connection of power switches assigned to the single one of the lines adapted to transmit information between the control unit and the device, the power switches adapted to (a) block and/or (b) let through (a) positive and/or (b) negative current.
 46. The system according to claim 45, wherein the power switches are drivable by the control unit.
 47. The system according to claim 30, wherein the drive includes a rectifier, fed from the lines, having (a) unipolar and/or (b) rectified output voltage having a negative and positive potential.
 48. The system according to claim 47, wherein the negative potential is arranged as a reference potential.
 49. The system according to claim 29, wherein (a) signal electronics of the drive are provided at a negative potential and/or (b) a voltage between electrical contacts of components of the signal electronics and the negative potential is always lower in terms of absolute value than the voltage to a positive potential.
 50. The system according to claim 29, wherein the apparatus includes two power switches connected to the control unit, each power switch connected in parallel to a respective diode that is external to the power switch and connected in series to each other, each diode being positioned on the single one of the lines adapted to transmit information between the control unit and the device; wherein the two power switches are configured to switch between four different states of supply voltages of the AC supply-voltage source: (i) a first state where current is blocked; (ii) a second state where only a positive current is enabled; (iii) a third state where only a negative current is enabled; and (iv) a fourth state where the current is completely conducted; and wherein the apparatus is adapted to switch the series connection of power switches between the four different states of the supply voltages of the AC supply-voltage source one after another in time to code the information on the single one of the lines adapted to transmit information between the control unit and the device.
 51. A method for operating a system including an apparatus, having a control unit, connected to a multi-phase AC supply-voltage source, and a device connected to the apparatus via a plurality of lines, each line corresponding to a respective phase of the AC supply-voltage source, comprising: supplying AC voltage from the apparatus to the device via the lines to power the device; transmitting information between the control unit and the device by a single one of the lines adapted to transmit information between the control unit and the device; measuring supply voltages of the lines; forming a difference between the measured supply voltage of the single one of the lines adapted to transmit information between the control unit and the device and the measured supply voltage of at least one other line; and performing a curve evaluation to evaluate the measured voltage associated with the single one of the lines adapted to transmit information between the control unit and the device, the curve evaluation including amplifying the measured supply voltage associated with the single one of the lines adapted to transmit information between the control unit and the device by a factor to an amplified value to uniquely identify information transmitted between the control unit and the device.
 52. The method according to claim 50, wherein the apparatus includes two power switches connected to the control unit, each power switch connected in parallel to a respective diode that is external to the power switch and connected in series to each other, each diode being positioned on the single one of the lines adapted to transmit information between the control unit and the device, the method further comprising: switching the two power switches among four different states of supply voltage of the single one of the lines adapted to transmit information between the control unit and the device: (i) a first state where current is blocked; (ii) a second state where only a positive current is enabled; (iii) a third state where only a negative current is enabled; and (iv) a fourth state where the current is completely conducted, one after another in time to code the information on the single one of the lines adapted to transmit information between the control unit and the device. 